1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) and a driving method thereof. More particularly, the present invention relates to an LCD and a driving method that reduces the degree of flicker and image sticking.
2. Description of the Related Art
An LCD comprises a liquid crystal panel having a thin film transistor (TFT) substrate on which a TFT is formed, a color filter substrate on which a color filter layer is formed, and a liquid crystal layer disposed between the two substrates. Since the liquid crystal panel is not self-emissive, a backlight unit may be provided in the rear of the TFT substrate. Light emitted from the backlight unit can pass through the liquid crystal panel. The transmittance of light through the liquid crystal panel depends on the alignment of the liquid crystal.
A gate line and a data line provided on the TFT substrate intersect each other, thereby forming a pixel. Each pixel is connected to the corresponding TFT. A gate on voltage Von is applied to the gate line, and therefore the TFT is turned on, thereby a data voltage Vd applied through the data line is applied across the pixel. The alignment of the liquid crystal varies in accordance with an electric field formed between a pixel voltage Vp across the pixel and a common voltage Vcom formed in a common electrode of the color filter substrate. The data voltage Vd is applied by frame with opposite polarity.
The data voltage Vd applied across the pixel is dropped by a parasitic capacitance Cgs formed between the gate electrode and the source electrode, thereby generating the pixel voltage Vp. The voltage difference between the data voltage Vd and the pixel voltage Vp is known as the kickback voltage Vkb.
The kickback voltage Vbk varies according to the grayscale and polarity, thereby causing the pixel voltage Vp to vary by frame. This induces both flicker caused by a brightness difference and image sticking (in which a fixed image remains immediately after its display as if it had been burnt in) caused by a residual DC voltage. Flicker and image sticking cause the quality of the display to deteriorate.
A need therefore exists for an LCD and a driving method that reduce the degree of flicker and image sticking.